Zika may not be the only virus of its kind that can damage a fetus

Tests on pregnant mice show two other flaviviruses also cause deadly harm in the womb

ALL IN THE FAMILY West Nile virus (green) grows in a lab sample of human placental tissue in this micrograph. Like Zika, West Nile can harm a fetus, tests in mice show.

Nitin Arora and Carolyn Coyne/University of Pittsburgh

Zika virus may not be the black sheep of the family. Infections with either of two related viruses also cause fetal defects in mice, researchers find.

Some scientists have speculated that Zika’s capacity to harm a fetus might be unique among its kind, perhaps due to a recent change in the virus’s genetic material (SN: 10/28/17, p. 9). Others have argued that perhaps this dangerous ability was always there. It just wasn’t until the 2015–2016 epidemic in the Western Hemisphere that enough pregnant women were affected for public health researchers to identify the association with fetal defects (SN: 12/24/16, p. 19).

But new work suggests this capacity is not Zika’s alone. Pregnant mice infected with West Nile or Powassan virus — both flaviviruses,

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